API returns incorrect response when a pool has multiple ns records

[Paul Glass]

To reproduce:

Update a zone's pool to have multiple different NS records:

PATCH /v2/pools/794ccc2c-d751-44fe-b57f-8894c9f5c842
{
    "ns_records": [{
        "hostname": "ns1.example.com.",
        "priority": 1
    },{
        "hostname": "ns2.example.com.",
        "priority": 1
    },{
        "hostname": "ns3.example.com.",
        "priority": 1
    }]
}

Then fetch the NS records for a zone:

GET /v2/zones/e2634cf2-0e9c-4730-9cb1-4720bfca06f9/recordsets?type=NS
{
  "recordsets": [
    {
      ...
      "records": [
        "ns3.example.com.",
        "ns3.example.com.",
        "ns3.example.com."
      ],
      "type": "NS",
      ...
    }
  ...
}

The API returns the right number of NS records, but all of the records are the same when they should match the ns_records list for the pool.

Other notes:
- Querying the nameserver(s) will return the correct NS records
- This doesn't seem to be a problem with zone exports. An exported zone will have the correct NS records based on the pool.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/226317

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/226317
Committed: https://git.openstack.org/cgit/openstack/designate/commit/?id=93d572e47a8d4b59462ddfea33cd6224adb9b55d
Submitter: Jenkins
Branch: master

commit 93d572e47a8d4b59462ddfea33cd6224adb9b55d
Author: Endre Karlson <email address hidden>
Date: Tue Sep 22 15:18:10 2015 +0200

    Ensure unique records when listing recordsets

    Add a test also to always ensure that the records are unique.

    Change-Id: Iddc451ec2c99c51260273fbbabebb1c00c79e74d
    Closes-Bug: #1493942